1. Field of the Invention
The present invention relates to a mobile communication terminal, and particularly, to a multimedia mobile communication system and method for updating functions of a mobile communication terminal.
2. Description of the Related Art
Generally, a mobile communication system allows a user to communicate with another party through a mobile communication terminal. The communication may be conducted at anytime, any place and while the user is moving. The mobile communication terminal maintains the communication while the user is moving by being wirelessly connected to a mobile base station of a corresponding service area.
An initial system of the mobile communication system, such as a first generation system, uses a voice-grade signal to communicate with another party. A second generation system uses the existing mobile communication system as is, but additionally uses a text and a symbol signal to communicate with another party. A third generation partnership project (3GPP) mobile communication system is a multimedia communication system for communicating voice, text and image signals.
The 3GPP mobile communication system is capable of processing mass image data. Accordingly, the system requires a new concept radio signal transmission method to expedite processing of the image data as well as other data. The 3GPP mobile communication system is divided into a Time Division Synchronous Code Division Multiple Access (TD-SCDMA) system for Mobile Communication developed from a Global System for Mobile Communication (GSM) and a Wideband Code Division Multiple Access (WCDMA) system developed from a Code-Division multiple access (CDMA) system.
As for the 3GPP TD-SCDMA mobile communication system, there are many technical differences between itself and the second generation GSM mobile communication system. First, a 3GPP system construction is different from that of the second generation GSM mobile communication system, as it takes a long time to build a complete 3GPP TD-SCDMA system. For this reason, a transitional technology in between the second and third generation of systems is required. Such a transitional technology is a 2.5th generation TD-SCDMA system (hereinafter referred to as TSM).
TSM is a system for providing a multimedia communication service using a GSM of an existing second generation Time Division Multiple Access (TDMA) system and a General Packet Radio Service (GPRS) mobile communication system network structure. The 2.5th generation TD-SCDMA system has been expected to have the following problems: small data transfer rate, low number of services, relatively low quality of services and a relatively short technology lifespan in comparison with the 3GPP TD-SCDMA system.
In addition, a separate mobile communication terminal is required for the TSM and the 3GPP TD-SCDMA. Accordingly, a financial burden is imposed on both a subscribers side and a service provider's side. It is therefore necessary to develop a new multimedia mobile communication terminal commonly using the TSM and the 3GPP TD-SCDMA.
FIG. 1 is a block diagram showing a multimedia mobile communication terminal according to the related art. A radio frequency (RF) switch 10 selects an RF signal received by an antenna (ANT) based on a control signal from a control unit 60 and applies the selected RF signal to an RF receiving unit 20.
The RF receiving unit 20 detects the RF signal containing a communication signal and applies the detected RF signal to an analog-to-digital converter (ADC) 30. The ADC 30 converts the analog RF signal into a digital RF signal and outputs the converted digital RF signal to a down-converter circuit 40. The down-converter circuit 40 converts the digital RF signal into a digital intermediate frequency (IF) signal and outputs the digital IF signal to a baseband processing unit 50.
The baseband processing unit 50 converts the digital IF signal into a baseband signal, decodes the baseband signal to convert the signal into a multimedia signal and applies the multimedia signal to the control unit 60. The control unit 60 then outputs the multimedia signal to a corresponding path and controls/monitors an operation of the mobile communication terminal.
Thereafter, the multimedia signal outputted from the corresponding path is applied to the baseband processing unit 50 by the control unit 60. The baseband processing unit 50 encodes the multimedia signal to convert the signal into a digital baseband signal and applies the digital baseband signal to the up-converter circuit 70. The up-converter circuit 70 up-converts the digital baseband signal into a digital IF signal and outputs the digital IF signal to a digital-to-analog converter (DAC) 80.
The DAC 80 converts the digital IF signal outputted from the up-converter circuit 70 into an analog IF signal and applies the analog IF signal to an RF transmitting unit 90. The RF transmitting unit 90 up-converts the analog IF signal into an RF signal and applies the RF signal to the RF switch 10. The RF switch 10 then applies the RF signal to the antenna based on a control signal from the control unit 60, wherein the RF signal applied to the antenna is outputted by radio. The RF switch 10 selects the transmission and reception path for the RF signal based on a control signal applied from the control unit 60.
As so far described, in the multimedia mobile communication terminal according to the related art, all signal processing components are implemented in hardware and process only a preset function. Therefore, when specific functions are to be updated or added, the hardware components corresponding to the respective functions need to be restructured. Particularly, the DAC 80, the ADC 30, the up-converter circuit 70 and the down-converter circuit 40 are units which should be newly restructured when a specific function of a mobile communication terminal is updated from TSM to the 3GPP TD-SCDMA system.
Accordingly, because functions of the related art multimedia mobile communication terminal operated in the TSM system cannot be updated or supplemented by the 3GPP TD-SCDMA system, a new mobile communication terminal adopting the 3GPP TD-SCDMA is required.